1. Field of the Invention
This invention relates to an X-Y stage for adjusting the position of a patterned wafer for macro and micro optical inspection and, more particularly, to a mechanism for accurately shifting the wafer from the macro optical axis to the micro optical axis at which the respective inspections are to occur.
2. Description of the Prior Art
It is well known to use a crossed roller type stage to move a patterned wafer in two orthogonal axes during manual operator micro inspection of a wafer. Where two optical systems are to be incorporated in one wafer inspector, it is necessary to move the wafer from one station to the other. In addition, a similar increment of travel is still required at each station. While such movement could be accomodated by the crossed roller technique alone, stage size would be increased by the need to move the distance between two optical systems, in addition to the movement required at each station separately. This invention discloses a technique for using a small stage, capable of only moving the distance required at one station, on which is mounted an arm and a chuck which can be moved a precise fixed distance. The distance in this case being equal to the distance between optical systems. This technique is less expensive, smaller in size and faster in operation than a single stage capable of the entire range of movement.